1. Field of the Invention
The present invention relates to spring mechanisms used with cylindrical locks to support a lever handle in a horizontal orientation and to return the lever handle to horizontal after the handle is rotated.
2. Description of Related Art
Cylindrical locks include inner and outer handles mounted on corresponding spindles that extend outward from opposite sides of a central lock core mounted within a bored opening in a door. In designs intended for use with conventional round doorknobs, the lock core will typically include a spring return mechanism capable of returning a doorknob to its initial position after it is rotated.
However, when lever handles are installed, the spring return mechanism within the lock core is normally supplemented with lever handle return springs that are capable of supporting the lever handles and returning the handles to their initial horizontal orientation. Unlike a cylindrically symmetrical doorknob, the center of gravity of a lever handle is offset from its axis of rotation. This offset constantly applies a gravitational torque to the lever handle due to the weight of the lever portion of the handle. The gravitational torque must be overcome by the lever handle spring return mechanism when returning the handle to horizontal.
Conventionally, the lever handle return springs are mounted on the outer surface of the door in a rose surrounding the base of the handle. This produces a relatively thick and bulky undesirable appearance for the rose. A thinner appearance for the rose is preferred than is presently available.
The rose also preferably provides a stop for the rotation of the lever handle. In order to perform this function, and to provide the thickness required to hold the springs within the rose, the main structural base of the rose has heretofore been formed by casting, or by machining it from a relatively thick initial block of material. Producing the rose in this way is expensive. A less expensive method of  construction for the principal structural elements of the rose is desirable that still retains the strength required in a lever handle design.
A further difficulty with existing lever handle return spring mechanisms relates to the clearances required, which can provide an undesirably “loose” feel to the mechanism. Reductions in the clearances to provide an improved feel are difficult in existing designs without unduly increasing cost.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a lever handle return spring assembly that has a reduced visual thickness.
It is another object of the present invention to provide a lever handle return spring assembly that is strong and resistant to lever handle abuse and yet may be constructed at reduced cost compared to earlier designs.
A further object of the invention is to provide a lever handle return spring assembly that has an improved “smooth” feel by reducing friction.
It is yet another object of the present invention to provide a lever handle return spring assembly that has an improved “tight” feel by reducing internal clearances.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.